The seed bank project at the Geneva Conservatory and Botanical Garden (CJB)
In 2000, a brand new section was initiated at the CJB, dedicated to the conservation of endangered regional flora. In particular, a seed bank was to be gradually implemented.
In Switzerland, most of the famous flora is alpine, but major losses were among the species of the lowland flora. For example, land use has totally changed between 1985 and 2009 on 15% of the territory. To maintain the biodiversity of the flora, it is essential to preserve the variability of species and populations in the most threatened areas. The Red List of vascular plants in Switzerland shows that 30% of flora is endangered. The Red List of the Geneva flora (2006) points out that 327 species (25%) are endangered and 158 (13%) seem to have disappeared since the beginning of the 20th century. Threatened flora is often linked to increasingly damaged environments subject to strong pressures such as dry meadows, wetlands, shorelines or ruderal areas.
A seed bank project seemed to be an appropriate response to these alarming facts and an achievable goal for our institution.
Why a seed bank project?
Seed banks following international standards such as the Millennium Seed Bank or the Universidad Politécnica in Madrid did not exist in Switzerland in 2000. It was important to start such a project in order to achieve the objectives of the Global Strategy for Plant Conservation (GSPC): retain 75% of the flora in ex situ conservation and dedicate our efforts to the national and regional plant species.
As usual in temperate climates, most plant species in Switzerland produce orthodox seeds. Seed banking proved to be the most efficient method for storing accessions of a large number of plant populations for a long time. In the garden, we have the opportunity to produce seeds or to multiply plants for translocations projects. To harvest seeds, we can benefit from the campaigns planned for the Index Seminum.
Several laboratory activities were already underway in the institution. Implementing facilities for seed banking seemed to be an achievable goal and the most suitable tool to maintain as many species as possible. This option was preferred to in vitro culture and can be supplemented for some species by ex situ cultivation in the garden.
What are the objectives of seed banking activities?
Considering the budgets and resources available, the focus is oriented on threatened species at national and regional level. In the beginning, certain categories of species were preferred, especially segetal species, highly endangered throughout Switzerland or species with high longevity seeds.
Gradually, collaboration with the Nature Conservancy Agency of Geneva has developed around conservation projects and resulted in the signing of an agreement with the CJB. Among other activities, inventories of vascular plants, mapping natural environments, a Red List and a geographic information system were completed. In this context, we have focused in recent years on the harvesting activities of endangered plants in the region.
One the one hand the goal is to maintain the regional genetic variability of plants by collecting samples of many endangered populations. On the other, the collected seeds may be used for translocation projects such as reintroductions, reinforcement or even introductions. The seed bank proved to be very useful to safeguard seeds of endangered plant populations or threatened by buildings.
The objective for Geneva is to aim at having at least one sample of all endangered and nearly threatened species. For the rest of Switzerland, partnerships and opportunities allow to collect plants from the Swiss or regional Red Lists, especially in relation to conservation projects. The seed samples are divided into two types of containers, some for long-term storage and the other for short-term storage. The long storage samples are duplicated, the second duplicate being sent to the crop seed bank of Agroscope (Vaud). The short term samples may be used for ex situ multiplication to meet the needs of conservation projects of some highly endangered species or for research purposes.
How to collect and conserve seed for a long time?
Several existing protocols (ENSCONET, MSB, UPM, APAT-CBNM, etc.) were studied to establish collecting and curation protocols adapted to the climate and available facilities.
In short, since 2008, the main guidelines of CJB protocols are following:
- Harvest: collecting a sufficient number of mature, viable and healthy seeds to obtain a genetically representative sample of the population. The harvest is limited to 25% of the viable seeds and must be spread over at least 40 mother plants;
- Pretreatment: ripening and cleaning in optimal conditions, weighing, counting and cut-test, data collection in CJB Conservation data base;
- Curation protocol: drying to equilibrium with 15% rH at 18oC temperature within dry room, humidity test, conditioning in 2 surrounding glass hermetic containers (flame sealed Pyrex glass tubes in Kilner jars), security labeling, storage at -18oC in freezer.
- Standardized germination tests after 6 months in freezer, no regeneration, visual control of samples through glasses (silicagel).
The main concern is to ensure a long-term hermetic storage to keep the viability of seeds at the same level as at harvesting time.
Late 2014, 440 taxa and 1131 samples were collected for the seed bank, 3891 tubes were sealed and about 23’800’000 seeds were stored in the freezer.
During the last decades, conservation projects were developed for some endangered species. Actions plans were drawn up for 16 endangered taxa of the Canton, some with French partners of the Lake Geneva region. Among other conservation measures, ex situ collection of seeds and multiplication of seed bank samples for reinforcement or reintroduction were applied and monitored in subsequent years. In some cases, these techniques have been used in case of destruction of plant populations on construction sites.
The action plans describe measures that can normally be scheduled, but backup measures on construction sites are often done in a hurry. All measures face some random conditions and can not be totally controlled. Therefore many actions are not conducted on a scientific basis, but the monitoring results are used to draw conclusions about the success and feasibility of such practices. In all cases, the seed bank and the ex situ culture have proven to be very helpful in supporting the conservation of the natural flora.